The subject matter disclosed herein relates to turbine combustors, and, more particularly, to a system for damping oscillations in a turbine combustor.
A gas turbine engine combusts a fuel-air mixture in a combustor, and then drives one or more turbines with the resulting hot combustion gases. The turbine combustor may use dry low NOx (DLN) combustion. In DLN combustion, fuel and air are pre-mixed prior to ignition, which lowers emissions. However, the lean pre-mixed combustion process is susceptible to flow disturbances and acoustic pressure waves. For example, acoustic pressure waves may travel through a hot section of the turbine combustor formed by a liner and a transition piece, a cold section of the turbine combustor upstream from the liner, and a plenum upstream from fuel nozzles in the turbine combustor. Flow disturbances and acoustic pressure waves could result in self-sustained pressure oscillations at various frequencies. These pressure oscillations may be referred to as combustion dynamics. Combustion dynamics can cause structural vibrations, wearing, and other performance degradations. Unfortunately, DLN combustors have certain design features, which can complicate the mitigation of these pressure oscillations.